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Josephson Junction Materials Research Using Phase Qubits



Raymond W. Simmonds, Dustin P. Hite, Robert McDermott, Matthias Steffen, Ken B. Cooper, Kristine Lang, John M. Martinis, David P. Pappas


At present, the performance of superconducting qubits is limited by decoherence. Strong decoherence of phase qubits is associated with spurious microwave resonators residing within the Josephson junction tunnel barrier [1]. In this work, we investigate three different fabrication techniques for producing tunnel junctions, varying the properties of the superconductor-insulator interface, and through experimental measurements, we characterize the junction and corresponding qubit quality. We find that there is a strong correlation between the morphology of oxidized base electrodes and the lowering of subgap currents in the junction I-V characteristics, while there is no noticeable improvement in the performance of fabricated phase qubits. Thus, 'traditional' indicators of junction performance may not be enough to determine qubit performance. However, truly crystalline insulating barriers may be the key to improving Josephson junction based qubits.
Proceedings Title
Quantum Computation: solid state systems
Conference Dates
June 7-10, 2004
Conference Location
Naples, IT
Conference Title
Macroscopic Quantum Coherence and Computing


decoherence, Josephson tunnel junction, Materials research, Quantum computing
Created May 30, 2006, Updated February 17, 2017